1. Field of the Invention
The present invention relates to a mechanical pencil provided with a slider.
2. Background Art
Mechanical pencils adapted to advance a lead by a knocking operation are conventionally used. In using such mechanical pencils, a lead is advanced and exposed from its distal end by an appropriate length and the lead is further advanced by a knocking operation when the lead has become short by the use.
The known mechanical pencils are disclosed in the patent documents 1 and 2, the mechanical pencils each being provided with a slider having a lead guide at a distal end of the mechanical pencil, which guide is forced to slide to feed the lead in response to a remaining length of the lead so as to keep on being used.
Such mechanical pencils as disclosed in the patent documents each arrange the slider within a head section thereof. The slider is movable back and forth and includes an inner friction part to friction with a lead and an outer friction part to friction with an inner surface of the head section.
A tubular lead guide is fixed to a distal end of the slider and communicates with the inner friction part of the slider. In advancement of a lead toward the distal end by a knocking operation, the slider moves toward a distal side from a proximal side due to a frictional resistance between the lead and the inner friction part of the slider. In writing, the lead guide appropriately moves in response to a remaining length of the lead, so as to expose the lead by an appropriate length.
A chuck having a chuck portion is moved forward and backward with a collar (also called “a chuck ring”) for fastening the chuck by a knocking operation. The collar is disengaged from the chuck at a position during forwardly moving and the lead is advanced to the position. When the chuck portion is moved backward, the frictional resistance of the slider prevents the lead from being retracted with the collar disengaged, so that the lead is advanced by a predetermined length.
Patent document 1: JP 3-47907 Y
Patent document 2: JP 2560818 Y